examples/src/main/java/org/apache/spark/examples/ml/JavaBisectingKMeansExample.java
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.spark.examples.ml;

// $example on$
import org.apache.spark.ml.clustering.BisectingKMeans;
import org.apache.spark.ml.clustering.BisectingKMeansModel;
import org.apache.spark.ml.evaluation.ClusteringEvaluator;
import org.apache.spark.ml.linalg.Vector;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Row;
// $example off$
import org.apache.spark.sql.SparkSession;


/**
 * An example demonstrating bisecting k-means clustering.
 * Run with
 * <pre>
 * bin/run-example ml.JavaBisectingKMeansExample
 * </pre>
 */
public class JavaBisectingKMeansExample {

  public static void main(String[] args) {
    SparkSession spark = SparkSession
      .builder()
      .appName("JavaBisectingKMeansExample")
      .getOrCreate();

    // $example on$
    // Loads data.
    Dataset<Row> dataset = spark.read().format("libsvm").load("data/mllib/sample_kmeans_data.txt");

    // Trains a bisecting k-means model.
    BisectingKMeans bkm = new BisectingKMeans().setK(2).setSeed(1);
    BisectingKMeansModel model = bkm.fit(dataset);

    // Make predictions
    Dataset<Row> predictions = model.transform(dataset);

    // Evaluate clustering by computing Silhouette score
    ClusteringEvaluator evaluator = new ClusteringEvaluator();

    double silhouette = evaluator.evaluate(predictions);
    System.out.println("Silhouette with squared euclidean distance = " + silhouette);

    // Shows the result.
    System.out.println("Cluster Centers: ");
    Vector[] centers = model.clusterCenters();
    for (Vector center : centers) {
      System.out.println(center);
    }
    // $example off$

    spark.stop();
  }
}
